1. Field of the Invention
The present invention relates to a method for manufacturing a package in which an accommodated article is sealed in a cavity formed between two bonded boards, a method for manufacturing an SMD-type piezoelectric vibrator in which a piezoelectric vibrating reed is sealed as the accommodated article, and an oscillator, an electronic device, and a radio-controlled timepiece each having the piezoelectric vibrator.
2. Description of the Related Art
In the related art, a package in which a pair of boards is bonded together, and an accommodated article is sealed in a cavity formed between the boards is known. As one type of such a package, a piezoelectric vibrator utilizing quartz or the like is known which is used in a cellular phone and a portable information terminal as the time source, the timing source of a control signal, a reference signal source, and the like.
Although there are various piezoelectric vibrators of this type, an SMD-type piezoelectric vibrator is known as one example thereof.
As the SMD-type piezoelectric vibrator, a two-layered piezoelectric vibrator in which a base board and a lid board are directly bonded together, and a piezoelectric vibrating reed is accommodated in a cavity formed between both boards is known. The two-layered piezoelectric vibrator is suitably used in that it is excellent in achieving a thin profile. As an example of the two-layered piezoelectric vibrator, JP-A-2002-124845 and JP-A-2006-279872, for example, disclose a piezoelectric vibrator in which a piezoelectric vibrating reed and an outer electrode formed on a base board are electrically connected using a conductive member (penetration electrode) which is formed so as to penetrate through the base board.
As a method of forming the penetration electrode in a penetration hole formed in the base board of the piezoelectric vibrator, a method of filling conductive silver paste in the penetration hole and baking the silver paste, a method of disposing a conductive core material in the penetration hole so as to electrically connect both surfaces of the base board, filling a glass frit in other regions, and baking the glass frit, and the like are known.
However, when the penetration electrode is formed using the conductive core material and the glass frit, the volume of the glass frit will decrease during the drying and sintering steps. Therefore, in order to fill a desired amount of glass frit in the penetration hole, it is necessary to repeat the filling, drying, and sintering steps of the glass frit several times. Thus, there is a problem in that the manufacturing process takes a lot of labor and time, and thus the production efficiency decreases.